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Q & A Security · August 21, 2026

What's the difference between an IP blacklist and a domain blacklist?

IP blacklists (like Spamhaus ZEN) flag the sending server’s IP address — your email is rejected before the content is even read. Domain blacklists (like Spamhaus DBL, SURBL, URIBL) flag your domain name appearing in email bodies, URLs, or headers. Both affect email deliverability, but in different ways. You need to check both.

Read the full guide
How to Check If a Domain Is Blacklisted (Step-by-Step)
A domain blacklist listing can silently kill email delivery and trigger browser warnings. This guide walks through how to check any domain against 50+ blocklists, read the results, and take action.
Related questions
Can a domain be blacklisted even if I never sent spam? Do I need to check all blacklists or just the major ones? How long does delisting take?